The present invention relates to piezoelectric transducers for generating ultrasonic oscillations for disintegrating bladder, urethra and kidney stones, of the kind which comprises two piezoelectric discs clamped between two metal elements by means of a tubular bolt utilizable as a flushing passage, and whereof the metal element at the distal side may have a curbed tubular shaft transmitting the ultrasonic oscillations and joined to the flushing passage of the bolt screwed to it via an end fitting provided with a passage.
In known transducers of the kind referred to above, the shaft transmitting the ultrasonic oscillations, which has a curvilinear portion and acts as a flushing passage, had a comparatively small internal diameter along the area of curvature, and the flushing passage extending through the transducer comprises a rigid duct pipe connected to the transmitting element on the one hand, and to a flushing pipe on the other hand. It was discovered that the shaft used as a transmitter element tends to fracture in the area of the curvilinear portion and in the transition to the end fitting due to the longitudinal and transverse effects of the ultrasonic oscillations caused by the curvature, and that the oscillation conditions, and in particular the efficiency of power transmission, are effected deleteriously by the rigid pipe passing through the transducer. Moreover, the particles of material produced by disintegration of stones and intended to be extracted, rapidly settled, primarily within the passage extending through the transducer, so that fluid draining was no longer assured.
Consequently, it is an object of the invention to reduce or eliminate the tendency of the tubular shaft transmitting the ultrasonic oscillations to the stone which is to be broken up, to fracture in the area of the curvature and in draining the flushing fluid together with the matter to be removed in unobjectionable manner, without obstruction by the sonic oscillator.